Circuit breaker



Feb. 27, 1940.

1'. LINDsTRoM GIRCUITv BREAKER Filed Jan. 16,l 1936 3 Sheets-Sheet 1Feb. 27, 1940. T. LINDsTRoM CIRCUIT BREAKER 3 Sheets-Sheet 2 2754.

Filed Jan. 16, 1936 ATTORNEY Fb4 27f1940- 1'. I INIDSTRIMA 2,192,046

CIRCUIT BREAKER Filed Jan. 16, 1956 f 3 51199134119 .3

' WITNESSES: I INVENTOR i BY ATTORNEY Patented Feb. 27, 1,940

iuirsrir OFFICE" cmom'r Bauma Ture Lindstrom, Edgewood, Pa., assignor toWestinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., acorporation o! Pennsylvania Application January 1e, 193e, sensi No.sassil so claims.

A further object of the invention isthe `provision of a motor drivenoperating mechanism l for circuit breakers which, after being initiallyset into operation, is automatic to effect either opening, closing orresetting of the breaker contacts.

Another object of the invention is the provi- T sion of a motor drivenoperating mechanism for circuit breakers which readily permits manualoperation of the breaker when desired.

A still further and more specific object of the invention is theprovision of speed responsive means in motor driven circuit breakeroperating mechanisms lfor controlling the rotation of the driving motor.

An ancillary object of the invention is ,the provision of resilientactuating means in circuit breaker operating mechanisms of the motordriven type.

Other objects and advantages relate to details 'and the arrangement ofthe various parts of the novel operating mechanism and will appear morefully in the following description, when taken in connection with theaccompanying drawings, in which Figure 1 is a side elevational view,partially in section, showing a circuit breaker embodying the motordriven operating mechanism of, my invention;

Fig. 2 is an enlarged cross sectional view taken along line II-II ofFig. 1 showing a braking device for bringing the operating mechanism torest after operation of the breaker contacts has been accomplished;

Fig.v 3 is a side elevation of the brake mechanism illustrated in Fig.2, and shows `the casing and the brake lining in cross section; f

Fig. 4 is an enlarged cross sectional View taken along line IV-IV ofFig, 1, showing the internal construction of the driving mechanism andthe control switch for the driving motor;

Fig. 5 is a skeleton perspective view of the control switch for thedriving motor;

Fig. 6 is a schema-tic wiring diagram of theV motor control circuit;

Fig. 7 is a longitudinal section yview of the resilient connecting rodfor actuating the circuit 55 breaker mechanism;

(Ci. 20G- 92) Fig. 8 is 'a side elevation view showing the couplingmember for connecting the actuatingrod to the switch lever; y

Fig. 9 is a cross sectional viewof the-coupling member taken along lineIX-IX of Fig. 10; li

Fig. 10 is a cross sectional view of the coupling member taken alongline X--X of'Fig. 8;

Fig. 11 is a side elevation view partially in section showing a modifiedform of brake structure for bringing the operating mechanism to rest; 10

Fig. 12 is a top plan view of anotherI form of brake structure; and

Fig. 13 is a sidel elevation view, partly in cross section, of the brakestructure shown in Fig. 12.

Although the motor driven operating mecha- 15 nism of this invention isapplicable to the operation of circuit breakers of various types, itpossesses numerous advantages adapting it particularly to the operationof circuit breakers employing a snap action mechanism controlled by anoscillatable lever for opening and closing the contacts. The advantageof the snap action mechanism, as iswell known in the art, provides l aquick make and break for the circuit contacts,

which greatly reduces arcing and thus prolongs the life of the contacts.I have found that of the` various remote controlled operating deviceswhich have been devised for circuit breaker operation,l the motor drivenoperating mechanism is by far better suited for circuit breakers of thesnap action` type, since these breakers are generally limited to lowpower applications. It is, therefore, desirable to keep the powerrequirement for remote control within reasonable limits. The snap actionmechanism for eflectingI either the opening or closing operation of thebreaker requires the application of a considerable force upon theactuating lever, which force mustbe applied over the greater portion ofthe path of movement of the lever, that is, at least up to the time themake or'break of the contacts occurs. A solenoid operated mechanismwould require an unwarranted expenditure of energy to eiect theoperation. inasmuch as the speed of operation of the contacts iscontrolled Aby the snap action mechanism and is independent of the speedof operation of the actuating lever, a relatively low powered motormechanically coupled in speed reducing relation to the operatingmechanism may be employed,. thereby effecting a considerable saving inpower.

vHowever, due to the fact that the load ipon the actuating lever of thebreaker is suddenly reduced after the snap action mechanism has vgoneinto operation this will cause the driving motor to speed up and unlesssome means are provided for bringing the motor to rest quickly after thecircuit thereto has been broken and when the actuating lever has reachedthe end of its stroke, the motor will coast for a period oftimesuiiicient to start the breaker actuating lever in its movement inthe opposite direction. I have obviated this diculty by providing theoperating mechanism with a brake which is responsive to the speed of themotor. In one form of the invention the brake used is so designed thatit is ineffective while the motor is under load, but as soon as the snapaction mechanism of the breaker has completed itsroperation and the loadupon the motor has been reduced, the resultant increase in speed rendersthe brake operative so as to bring the operating mechanism to rest.

It also becomes necessary in snap action breakers, particularly breakersemploying a trip iree mechanism which requires a deiinite amount ofmovement of the actuating lever in the open contact direction forresetting the mechanism after it has been tripped by an overload, toprovide means whereby the requisite amount of movement of the actuatinglever will always be insured. The means herein employed consists inproviding a slightly greater path of travel of the motor drivenactuating means than is required to actuate the breaker lever.

In order to prevent damage to the breaker mechanism which may resultfrom forcefully bringing the actuating lever against its stops at eitherlimit of its path or travel, I provide a resilient connecting rodbetween the motor driven actuating mechanism and the breaker 'actuatinglever. v

.a further feature of the invention comprises means for releasing theoperative connection between the motor operating mechanism and thebreaker actuating lever in order to render the breaker manuallyoperative. The releasable connection becomes necessary inasmuch as thedriving connection between the motor and the reciprocating mechanismcomprises a worm and worm gear, which combination is non-reversibieinaction, but has the advantage of a high speed :reduction which isideally suited for the particular use here employed.

In general, to accomplish the releasable connection, l provide acoupling member upon the breaker operating lever which slidably receivesthe motor driven actuating rod and which iS normally latched to the rod.Means are provided for the insertion of a manually operable lever which,when inserted, unlatches the coupling member from the actuating rod andpermits the breaker to be manually operated.

Having generally pointed out the main features of my invention, a morespecific description thereof will now be given with particular referenceto the drawings, in which the refer ence numeral l designates a snapaction breakerv The actuating mechanism 1 comprises a cradlev 8 hingedlysecured to the trame 5 at one end, as

shown at 9. The other end of the cradle 8 designated at i0 is engaged bya latching member Il. The latching member H forms part of the trippingmechanism of the breaker generally designated at I2, which may be of atype more fully described in an application of Harry J. Lingal, SerialNo. 600,624, lled March 23, 1932, and assigned to the assignee of thisapplication, now Patent No. 2,047,239, issued July 14, 1936.

The cradle 8 and the switch arm 4 are joined by means of a pair oftoggle links i3 and M. 'I'he mechanism is actuated by a` lever la hingedto the frame 5 at It and connected through a coil spring i1, the upperend of which is joined to the lever I5 at i8 whereas the lower end isconnected to the .knee lil between the toggle links i3 and I4. It Willbe apparent that when the actuating lever l5 is in the position shown inFig. l that the action of the spring ll! tends to collapse the togglelinks l2 and M to maintain the contact arm il in the open position. Asthe lever l5 is moved to the left or to the on position, and as thepoint i8 crosses the center line between the pivotal point of the togglelink i3 with the cradle 8 and the knee joint i9, the spring B1 willcause the toggle links to straight en out thereby forcing the switch armi clownwardly to cause the contact 3 to engage the contact 2.

In opening the contacts, the foregoing operations and movements oi thevarious parts occur in the reverse order and are well known and need notbe further described. In the event that the contacts 2 and 3 have beenopened due to overload, the tripping mechanism l2 comes into playreleasing the latch member H allowing the end l0 ci the cradle 8 to moveupwardly under the action of the spring il', which also raises theswitch arm` 4 through the toggle con nections l2 and i4.

ln' order to .reset the breaker, the actuating iever l5 is provided withan offset extension 26 adapted to engage the cradle il so as to movethecradle downwardly when the lever l5 is moved in the oli position. .'Bypermitting the lever I5 to be moved a short distance in addition to thatrequired to normally open the breaker contacts, the end i0 of the cradle8 is made to engage the latching mechanism l2 to again reset the cradle.

The 'operating mechanism suitable for actu ating the breaker from aremote point is generally indicatedl at 2i, and comprises a frame 22which may be secured to one end of the circuit breaker casing by meansof screws Within the frame 22 is mounted a driving motor 24. Secured tothe upper end of the motor 24 and the frame 22 is a gear case 25 intowhich an extension of the armature shaft of the motor 24 extends. Uponthis extension is mounted a Worm 26 adapted to engage a worm gear 2lsecured in any well known manner to a shaft 28. The shaft 28 isjournalled in suitable bearings in the sides of the gear case 25 and isprovided at one end with a crank arm 29. The crank arm 29 has a crank.3i) journalled in aperture 35 of a resilient actuating rod generallydesignated at 3l. The actuating rod 3i is reieasably con'l nected to acoupling member 32 which, in turn,

will thus be seen that 24 ls rotated, 4

the worm 26 in mesh with the Worm gear 21, will impart rotation to thecrank pin 30, which, i'n turn, will oscillate the connecting rod Il andconsequently the switch lever I6 for opening, closing and resetting thebreaker. i

As was pointed out above, the resilient connecting'r'od 3| is desirablein order to prevent injury to the mechanism 1 due to the fact that, forsatisfactory operation, it is necessary to insure the maximum movementof the lever i5 along its path of travel. This maximum movement isobtained by making the throw of crank arm 29 slightly greater than'whatwould theoretically be required. In order to provide the requisiteresiliency, the connecting rod 3| is` constructed 'of two parts, namely,a tubular portion 35 (Fig. 7) and a cylindrical portion 36 adapted to betelescopically received by the former portion. The tubular portion 35has a bore 31 and a reduced end portion 38, which end portion also has abore 48 but of less diameter than the bore 31. The bore 40 is adapted toreceive and serves as guiding means for the end portion 4| of the member36. The member 36 also has an intermediate portion 42 oi vsomewhatgreater diameter. The bore 31 has a portion 43 of reduced diameter whichforms an annular shoulder or stop 44 for one end of a coil spring 45positioned within the bore 31 and surrounding the cylindrical portion42. The other end of the spring 45 is maintained in contact with anoilset collar which in this instance may be screwthreaded onto the outersurface of the tubular portion 35. The offset portion of collar 58provides an annular shoulder 5|, the depth of which corresponds to thedepth of the shoulder 44 and is adapted to contact substantially theouter half of the end convolution of the spring 45. The inner half ofthe left end convolution of the spring 45 is adapted to be engaged by aflanged collar 46 mounted upon the end vportion 42 and secured in placeby means of a key or pin 41 The inner half of the right-handendconvolution of the spring 45 is engaged by an annularV shoulder 53 ofan offset collar 52. The greater diameter of the collar 52 is adapted tobe re.

ceived by the smaller diametrical portion of the collar 56 and isslidable coaxially therein. The

collarv52 also has an outwardly facing annular shoulder 54 against whichthe enlarged end portion of the shaft 36 is adapted to be held inengagement. n

From the foregoing description, it will be apparent that when a force isapplied to the end portion 38 in a right-hand direction, that is, in adirection tending to compress the rod 3|, such force will be transmittedto the tubular portion 35, the shoulder 44, through the spring 45 to theshoulder 53 of the collar 52 which, in turn, engages the portion 36 andtransmits the resultant movement to the releasable connection 32. In theevent that thefforce applied to the portion 38 is in the oppositedirection, that to the left, the shoulder 5| will engage the spring 45which, in turn, transmits the force to the flanged collar 46 and sincethe latter is secured to the portion 42 of the shaft 36 will cause thelatter to move to the left. In the particular arrangement described, thecoil spring 45, regardless of the direction of the force applied at theportion 38, will always work in compression so as to provide a resilientconnection between the end` portions 36 and 38.

The coupling member 32 (Figs. 8, 9 and l0) comprises a lower saddleportion 68 adapted to' Aoperated lever 1|.

ing 61 therethrough. The opening 61 is for the purpose of slidablyreceiving the end portion 36 of the operating rod 3|. The clutch member66 is also provided at one end with a recess 68 in which may be nested acompression spring 69 for biasing the clutch member toward the actuatingrod 36.

The actuating rod 36 is provided with a notch 59, the length of which ispreferably slightly greater than the diameter of the clutch member 66 sothat when the notch 59 and the clutch member 66 are in registration, thespring 69 will urge the clutch member into engagement with the notch tothereby latch the operating rod 3| to the coupling member 32.

The upright portion 64 is also provided with a vertical bore 10 for thereception of a hand The lever 1| has its lower end tapered, as shown at12, which in coopera- A tion with the tapered portion 13 of the clutchmember 66 forces the clutch member to the left when the lever 1| isinserted in the bore 10. The movement of the clutch member 66 to theleft by the hand operating lever 1| is suilicient to unlatch theoperating rod 3| from the coupling member 32 and thus permits thecoupling member to be rocked back and forth with the break lever l5.

In order to prevent accidental displacement of the lever 1| from itssocket within the coupling member 32, an annular groove 14 is provided,which is adapted to register with the beveled end 13 of the clutchmember 66, thereby releasably holding the hand operated lever in place.In order to interrupt the circuit of the driving motor 24 by the timethe mechanism ac'- tuates the breaker contacts, I provide a cutoutswitch generally designated at 80 (Figs. 4 and 5). The switch 80 in thisinstance comprises a cylindrical insulating member 6| surrounded by anannular housing 82. The inner end of the member 8| has an outwardlyprojecting ange 83, the end face of which is seated in a circulardepression in the sideof the gear case 25 positioned in concentricrelation with respect to the shaitl.

Positioned'between the flange 83 and the housing 82 is a flanged ring 84which serves to cooperate with screws 94 passing therethrough andthrough the housing 62 to clamp the assembly to the side of the gearcase 25. circumferential surface of the insulating member 8| are mountedfour substantially semi-circular contact segments'l 85, 86, 81 and 88.The segments 85 and 81 are paired in axially spaced parallel relationwith the segments 66 and 88 respectively. The two segments of each pairare adapted to be bridged by a metallic brush 89 secured to a spring arm90, which is mounted upon an insulating brush holder 9|. The brushholder 9| is mounted upon the end of the shaft 28 and is adapted torotate therewith. It will be apparent that as the shaft 28 revolves, thebrush 89 will wipe across the contact segments to establish in turn anelectrical connection between the pairs lofcontacts 85, 86 and 81, 88respectively.

The function and operation of the switch will be more fully understoodwhen considered Upon the inner with the wiring diagram oi' Fig. 6. Inthis diagram, the numeral 95 designates a suitable source of current.One of the lines of the source 95 is connected by conductor 96 to oneterminal of the motor 24. The other terminal of the motor 24 isconnected by conductor 91 to a conductor 98, which joins the contactsegments 85 and 81. The segment 88 is connected by a conductor 99 to oneterminal of a push button switch generally designated at |90. Thecontact segment 9S is connected by conductor lill to one terminal of asimilar push button switch |92. The other terminals of the push buttonswitches |99 and i92 Aare joined by a conductor |03 which, in turn, is

connected by conductor |94 to the other line of the source 95.

The brush holder 9| is so positioned on the shaft 29 with respect to thecrank arm 29 that when the crank arm 29 is in the position as shown inFig. l, that is, with the switch lever i in the open position., thebrush 89 will be in engagement with the leading edges of the contactsegments 81 and 99. Thus, when the push button switch |99 is closed,current will be established from the source through the conductor 99,motor 24, conductor 91, conductor 98, segment 81, brush 89,

` segment 99, conductor 99, switch |99, conductor H33, and conductor |94back to the source 95. The motor circuit being complete will cause themotor to rotate the crank arm 29, thus causing the connecting rod 3i' tobe moved to the left and consequently moving the circuit breaker leveri5 toward the closed position.

When the lever I5 has reached the overcenter position of the spring I1where the contact actuating mechanism 'l will automatically close thecontacts, the circuit to the motor 2d may be interrupted. By the timethe contacts have been closed, brush 89 will have reached the ends or"the contact segments 91 and 89 and as soon as the brush leaves thesecontacts, the motor circuit established through the push button switch|99 will be automatically broken. It will be noted that the trailingends 93 of the contact segments 81 and 88 as well as the ends 92 of they contacts 85 and 8B are bent inwardly from the surface of theinsulating member 93 and form projections substantially in radialalignment with the leading ends of the contact segments adjacentthereto. The purpose of the respective projections 92 ,and 93 is toprovide a quick break as the brush 89 travels over the ends thereof andalso to insure a positive contact between the brush and the leading endsof the adjacent pair of contacts. In other Words, with the particularconstruction shown, it is impossible to have the operating mechanismstop at a time when the brush 89 is not in engagement with either pairof contact segments.

From the previous description it will be understood that the operatingmechanism, following the closing operation of the breaker contacts, wasmade to come to rest with the brush 89 in contact with the segments 85and B6. Now, in order to open the breaker, push button |92 is actuated,which establishes the circuit from the source 95 through conductor 9 6,motor 24, conductor .91, conductor 98, contact segment 85, brush 89,contact segment 86, conductor il, switch |92, conductor |03 andconductor |04 to the other line of the source 95. Upon the initiation ofthis circuit, motor 24 will drive the crank arm 29 in the same directionas previously described, but since the arm'has moved 180 from itsinitial starting point and is now on its return movement to the startingpoint, it will move the connecting rod 3|' to the right and consequentlythe vbreaker lever i5 to the open position. Prior to the time when thelever l5 reaches the open position, that is, after the mechanism 1 hasopened the contacts 2 and 3, the brush 89 leaves the projecting ends 92of the segments 85 and 8B thereby breaking the motor circuit.

In the event that the breaker trips out when it is under load, say dueto an overload condition, it will be necessary, as pointed out above, tomove the breaker lever i5 slightly beyond the open position whichrelatches the cradle il thoreafter enabling the contacts 2 and 3 to beclosed in a normal manner. When remote control operation is desired forresetting the breaker, it will be necessary to first actuate the openingpush button 592 and after the full open position has been reached, tothen actuate the push button |99 to effect closing of the breaker.course, be understood that the push 'button switches i9@ and i192 may beyof the self-holding type, thatis, after being initially actuated, asuitable holding circuit is energized for maintaining the contactsclosed which automatically releases and restores the contacts to theopen position at such time when the circuit is opened by the cutoffswitch 99. y Inasmuch as push button switches of this type are old andwell known in the art, it is deemed not necessary to further illustrateor describe the same.

As was pointed out above, it is characteristic of snap-action switchesto allow the contacts to close or open under the action of thesnapaction mechanism prior to the time the actuating lever reaches theend of its stroke. It will be apparent that immediatelyl after theactuation of the snap-actionmechanism 'l the load upon the motor 24 willbe greatly reduced. When the switch 9U is arranged to deenergize themotor slightly after the spring |1 has been moved over center, themarked reduction of the load on the motor will cause it to materiallyincrease its speed. Even after the cutoff switch 89 has disconnected themotor from the source of supply 95, the coasting effect without motorspeed reducing means would be suilcient to carry the operating mechanisminto the beginning ci the next sequence of breaker operation. In orderto bring the motor to rest promptly at the end of the breaker operation,I provide a centrifwgally controlled brake mechanism generally indicatedat IIB. This mechanism (Figs. 2 and 3) comprises a cylindrical housingmounted in coaxial relation with the armature shaft of the motor 29 uponthe frame 22. The housing iii is provided with a cover plate ||2, andhas a brake lining ||3 on its inner wall, the purpose of which willappear hereinafter. A concentric opening H4 in the lower wall of thehousing provides an entrance for the shaftr I |5,which shaft is anextension of the motor armature shaft and is coaxial with the worm 26.Upon the end of the shaft ||5 is mounted a circular brake shoesupporting plate ||6 and is secured for rotation therewith by means of ascrew ||1. Placed near the outer periphery of the plate HB are a pair ofdiametrically opposed pins H8. A brake shoe il!) of elongated form, asshown in Fig. 2, is pivotally mounted at one end upon each pin I8 andmay be retained in position by means of a washer and retainer key, asillustrated. The brake shoes Ii 9 are each provided with a U- shapedrecess i420 at their pivotal ends for the reception of a coil spring |2|which is adapted It will, of

to encircle the pin ||8 and have one of its ends anchored into the plate||6 at |22 and the other end in engagement'with the shoe I|9 for thepurpose of urging the brake shoes ||9 in a clockwise direction and`normally maintain them in contactwith stop members |24. Thus, as themotor 24 rotates the plate ||61in a counterclockwise direction, thebrake shoes IIS will tend to pivot about their pins IIB in acounterclockwise direction toward the brake lining 3 positioned on theinterior ofthe housing III... When the motor is'under load, that is,during the operation of the lever I prior to the time the snap actionmechanism 1 'automatically actuates the contact arm 4, the speed of themotor will not be suiiicient to bring the brake shoe surfaces |25 intoengagement with the brake lining I I3. However, as soon as the mechanism1 actuates the contact arm 4, the load on the motor will be greatlyreduced causing it to speed up, which increase in speed and theresultant centrifugal force acting upon the brake shoes IIS, will bringthe braking surfaces |25 into engagement with the lining H3, therebycausing the motor to decelerate which, after its speed has y beenreduced considerably, will come to rest as a res'ult of the frictionalforces of the operating mechanism.

In Fig. 11, a modined form of braking mechanism is shown. In thisinstance, the cylindrical brake housing |30 is provided with a capmember |3I which is preferably screw threaded onto the housing. Theinner upper wall of the cap member 13| is provided with a flangedannular recess |32 in which is seated an annular brake lining |33. Theextension ||5 of the motor shaft projects upwardly through the bottom ofthe housing |30 and has a pin |34 passing diametrically therethroughnear its upper end. Hinged to the pin |34 is a pair of brake arms |35,the free ends of which carry brake shoes |36. It will be apparent thatas the shaft ||5 is rotated, the centrifugal force acting upon the shoes|36 will cause them to move outwardly and upwardly toward the brakelining |33. 'I'he cap member I3| is adjusted with respect to the brakeshoes |36 so that during normal load conditions upon the driving motor24, the brake shoes |36 will be adjacent, but not in contact with, thelining |33. Then, as the motor 24 speeds up asa result of the loadthereon being reduced following the automatic actuation of the switchactuating' mechanism 1, the brake shoes |36 will be thrown intoengagement with the brake lining |33 to thereby retard the rotation ofthe motor. The side of the casing |30 may also be provided with an indexfinger |31 which, in connection with a suitable indexY placed upon theouter side wall of the cap member I3I and calibrated in revolutions perminute or other suitable units, greatly `facilitates the adjustmentl ofthe cap member with respect to the housing.

In Figs. 12 and 13 is shown another form of brake mechanism,particularly adapted-for the purpose at hand. The. reference number- |40designates a cylindrical brake housing closed at the bottom except for aconcentric opening |4|. for receiving the extension I|5 of the armatureshaft of the motor 24. The shaft I|5 has a threaded portion l|42 adaptedfor threaded engagement with a circular, brake shoe supporting plate |43which plate is similar in construction to the plate ||6 shown in Figs. 2and 3. A pair of non-symmetrical. lli-shaped brake shoes |44 Aarepivotally mounted at one end upon pins |45,

the lower'ends of which have a threaded portion of reduced diameter forvthreaded engagement with the supporting plate |43 at diametricallyopposed points.

The configuration of the brake shoes |44 is such that when mounted, asshown in Fig. 12, the free or longer end |46 of each shoe is normallyinterposed between the two legs of the other shoe. A coil spring |41engaging a pin l|48 seated in the body of each shoe |44 at a pointadjacent the pivotal pins |45 normally maintains the shoes in acollapsed position and in engagement with the reduced end portion |49 ofthe shaft II5. It will be noted that the end portion |46 of'each' shoe|44 normally extends inwardly beyond the line joining the centers of thepivotal pins |45, thus when the supporting plate |43 is rotated, thecentrifugal force acting upon the end portions |46 on one side of theline joining the pivotal points |45, will have a tendency to rotate thebrake shoes |44 in a counterclockwise direction about their pivotalpoints |45, as viewed in Fig. 12, and to maintain the shoes inengagement with the shaft |49. The centrifugal force acting upon themain portion of the shoes |44 on the other side of the line joining thepivotal points |45 will tend to rotate the shoes in a clockwisedirection. v

The shoes |44 are designed with respect to shape and mass so that thecentrifugal force tending to cause rotation thereof in the clockwisedirection will predominate. The spring |41, is, therefore, one ofrelatively low tension but suiiicient to prevent an appreciable movementof the brake shoes outwardly in a clockwise direction at normal loadspeed of the driving motor ,24. 'I'hen as the motor 24 speeds up as aresult of the load thereon being reduced following the automaticactuation of the switch mechanism 1,

the centrifugal force acting upon the brake shoes I I4 will overcome theforce exerted by the spring |41 to cause the braking surfaces |50 of theshoes |44 to engage the inside wall of the casing and to thereby causethe motor to come to rest.

It is apparent that as soon as the brake vshoes |44 begin to. moveoutwardly and the mass of the end portions I46'begin to shift to theopposite side of the line joining the pivotal points |45, thecentrifugal forces tending to maintain the shoes inthecollapsed'position are reduced whereas the forces causing the shoes torotate outwardly are amplified to a high degree. Since the tension ofthespring |41 is relatively low. the restoring action of the brake shoes totheir collapsed or non-braking position is materially delayed, thuspermitting the braking action 'to continue until the speed of rotationof the mo-v tor is substantially zero.

.The particular design of the brake shoes |44 also aiords anadvantage inthat the distance between the braking surfaces |50 and the pivotal axis|45 .of the shoes is small as compared with the effective length of thebrake shoes be'- yond the braking surfaces, thereby making it possibleto obtain a relatively high brake contact pressure.

From the foregoing description, it will be apparent that Ihave provideda simple and vemcient operating mechanism for circuit breakers ofmoderately low power thereby aording remote control for these breakersat a moderate cost. The provision of a centrifugally operated brakewhich is positive in action and free from trouble for reducing thevcoasting period of the i the appended claims.

-resi1ient operating rod of the mechanism. A- further desirable featurewhich I have made possible through this invention and as described inthe foregoing isl the provision of means whereby the motor drivenconnection to the breaker operating lever canl be quickly andconveniently released so.l as not to impair the manual operatingfacilities of the breaker.

As has previously been pointed out, the circuit to'the motor 24 may beinterrupted when the lever I5 has reached the position where the contactactuating mechanism will automatically close the contacts of thebreaker, i. e., when the spring i7 passes over center. In such instancethe motor will not speed up after actuation oi the contacts as it hasbeen deenergized. Obviously under these conditions the centrifugal brakemechanism would be arranged to be actuated by the increase of speed ofthe motor before the motor circuit is deenergized, i. e.,before thespring Il passes over center.

Although I have shown and described a particular structure foraccomplishing motor driven operation of a snap action type breaker, itis to be 'understood that the same is for illustrative purposes and thatchanges and modiiications may be made by those skilled in the artwithout departing from the spirit and scope of I-claim as my invention:

1. In combination, a pair of separable contacts, a snap action mechanismfor opening and closing said contacts, an oscillatable lever foractuating said mechanism, means for actuating said lever comprising anoperating member, driving means for oscillating said operating member,means controlled by the position of said driving means for controllingthe operation of` said driving means, and means responsive to the loadconditions on said operating member for bringing said driving means torest following actuation of said mechanism.

2. In combination, separable contact means, a snap acting mechanism foropening and closing said contact means, an oscillatable lever foractuating said mechanism, means for actuating said lever comprising anoperating member, driving means including an electric motor foroscillating said operating member, means for automatically deenergizingsaid motor following ac-4 tuation of said snap acting mechanism, andmeans responsive to a reduction in load on said motor for retardingrotation of said motor.

3. In a circuit breaker, separable contact means, a mechanism foropening and closing said contact means, an oscillatable lever foractuating said mechanism, means including an electric motor foroscillating said lever, means for automatically deenergizing saidl motorwhen said lever reaches predetermined positions following actuation ofsaid mechanism, and aI brake operable in response to the occurrence of apredetermined speed condition of said motor for retarding rotation ofsaid motor.l

4. In combination, a pair of separable contacts, a snap action mechanismfor opening and closing said contacts, an oscillatable lever foractuating said mechanism, said mechanism being adapted to actuate saidcontacts before said lever reaches the ends of its normal path of traveland to eiect a decrease in the operating effort required to move saidlever on to the end of its path of travel following actuation of saidcontacts, driving means including an electric motor for oscillating saidlever, and means operable following actuation of said contacts forautomatically stopping said driving means immediately after said leverreaches the end of its path of travel and before its direction ofmovement is reversed by said driving means.

5. In combination, a pair of separable contacts, actuating mechanism forsaid contacts including an oscillatable lever for normally opening andclosing said contacts, a member releasable to cause'opening of saidcontacts irrespective of the position of said lever, means operable inresponse to predetermined conditions to effect release of said member,said member being resettable following its release by movement of saidlever in one direction, means for actuating said lever to open and toclose said contacts and to reset said releasable member comprising arotatable crank arm, a motor rotatable in one direction only for drivingsaid crank arm and resilient coupling means for operatively connectingsaid crank arm and said lever.

6. In combination, a pair of separable contacts, a mechanism for openingand closing said contacts including an oscillatable lever for normallyactuating said mechanism to open and to close said contacts, a memberreleasable to cause said mechanism to open said contacts irrespective ofthe position of said lever, means operable in response to predeterminedconditions to effect release of said member, said member beingresettable foliowing reiease thereof by movement of said lever in onedirection, means for actuating said lever to open and to close, saidcontacts and to reset said releasable member comprising a motor drivingmeans for oscillating said lever, and means including a brake responsiveto a predetermined change in speed of said driving means for bringingsaid driving means to a stop following actuation of said mechanism bysaid lever.

7. In combination, a pair oi' separable contacts, a snap actionmechanism for opening and closing said contacts including ancscillatable lever for normally actuating said mechanism to open and toclose said contacts, a member releasable to cause said mechanism to opensaid contacts irrespective of the position of said lever, means operablein response to predetermined conditions to effect release oi' saidmember, said member being `resettable following release thereof bymovement of said lever in one direction, means for actuating said leverto open and to close said contacts and to reset said releasable' membercomprising a motorV driving means for oscillating said lever, means forautomatically deenergizing said motor means following each actuation ofsaid mechanism by said motor means, and means including a centrifugallyactuated brake for said motor means operable in response to apredetermined change in speed of said motor means for causing said motormeans to stop immediately after said lever reaches either end of itspath of travel and bea snap action mechanism for opening and clos-`.2,192,046. i v v7 fore the direction of movement of 'said lever isreversed.

8. In combination, a circuit breaker having a pair of separable contactsand a. snap action mechanism for opening and closing said contacts andan oscillatable lever manually operable for actuating said mechanism,means for oscillating said lever to actuate said mechanism including arotatable crank arm, a motor for driving said crank arm, and couplingmeans including a clutch for -releasably-connecting said crank arm withsaid lever, said clutch being disengageable to permit said lever to bemov'ed manually independently of said crank arm.

9. In combination, relatively movable contacts,

ing said contacts including an oscillatable lever movable betweentwo'limiting positions for actuating said mechanism, said mechanismbeing adapted to actuate said contactsduring the movement of said leverin either direction before it reaches the end of-its path of-movement,the force required to move said lever being decreased after it has beenmoved a predetermined distance, means for oscillating said lever toactuate lsaid mechanism comprising a rotatable crank arm, an electricmotor for driving said crank ik arm, means connecting said lever to saidcrank.

arm, means for automatically deenergizing said motor when said leverapproacheseither of its limiting positions, and means including a brakeassociated with said motor operable in response to a predeterminedincrease inspeed of said Amotor for retarding the speed of said motor,

said brake comprising at'least a pair of centrifugally actuated brakingmembers biased to a non-braking positionwhich are moved to brakingposition in response to said predetermined increase in speed of saidmotor.

10, In a circuit interrupter, a pair of separable contacts, a snapaction mechanism for opening and closing said contacts, an oscillatablelever for actuating said mechanism, said mechanism being adapted toautomatically actuate said contacts prior to the time said lever reachesthe ends of its normal path of travel,

'driving means including a motor for actuating said lever,l lmeansactuated in timed relation with said lever for said motor when saidlever reaches predetermined positions, and speed responsive meansassociated with said motor for retarding the rotation thereof followingthe actuation of said lever to cause movement of said` contacts by said`mechanism.

1l. In a circuit interrupter, a pair or separable contacts, a snapaction mechanism for opening and closing said contacts, an oscillatablelever for actuating said mechanism, said mechanism being adapted toautomatically actuate said contacts prior to the time said lever reachesthe endv of its normal path of travel,

driving means including a motor for actuating said lever, means actuatedin timed relation with said lever for the motor when said lever reachespredetermined positions, anda centrifugally actuated brake responsive toan yincrease in speed of said motor to actnate said lever to cause theactuation of said contacts by said mechanism for retarding the rotationof said motor and bringing said lever to rest at the endof its stroke.

12. In combination, with a circuit breaker having a pair Vof separablecontacts and a mechanism including an oscillatable lever manuallyoperable for opening and closing said contacts, y

means for actuating said lever comprising rotary driving means, saidrotary driving means 1ncluding a crank arm, coupling means connectingsaid crank arm and said oscillatable lever, said coupling meansincluding aA clutch, and means for disengaging said clutch to releasethe operative connection between said crank arm and said lever tothereby render said lever operative manually independently of said crankarm and said rotary driving means.

13. In combination, with a circuit breaker having a pair of separablecontacts and a mechanism including an oscillatable lever manuallyoperable for opening and closing said contacts, means for `actuatingsaid lever comprising an oscillating tween said connecting means andsaid lever and to render said lever manually operative independently ofsaid oscillating mechanism and connecting means.

14. In combination, a circuit breaker having a pair of separablecontacts and an oscillatable le'ver manually operable for opening andclosing said contacts, power driven means for actuating said levercomprising a motor, a crank arm drivenby said motor, a member connectingsaid crank arm and said lever, releasable connecting means between saidmember and said lever adapted to receivea manuallyy operative removablemember, said connecting means normally providing a driving connectionbetween said member and said lever, said manually operative member whenin engagement with said connecting means being adapted to release thesaid driving connection and render the circuit breaker manuallyoperative by said oscillatable lever without moving said power drivenmeans'and` ing means comprising guide means secured to said lever forslidably receiving said rod, means for latching said guide means to saidrod ior movement thereby and a manually operable member for engagingsaid latching means for releasing the driving connection between saidrod and said guide means thereby to render the,

switch lever manually operative.

16. In combination, a circuit breaker having a pair of separablecontacts and an oscillatable lever for opening and closing the contacts,means for actuating said lever comprising a crank arm, a motor fordriving said crank arm, an actuating rod connected to said crank arm,connecting means secured to said lever including guide means forslidably receiving an end portion of said rod, said endA portion havinga notch therein, latch means associated with said connecting meansnormally biased into engaging relation with said notch, and a manuallyoperative handle removably associated with said connecting vmeansadapted to engage said latching means for rendering said connection andsaid lever movable relative to saidrod.

17. In combination, a circuit breaker having r.a pair of separablecontacts and an oscillatable lever for opening and closing the contacts,means resilient link; for operatively connecting.l said actuating meansand said lever, said resilient link havingy a force transmitting springmeans which transmits the force for operating the lever and which isalways Worked in compression irrespective of the direction. in whichsaid lever is moved.

18. In combination, a circuit breaker having a pair of separablecontacts and an oscillatable leverfor opening and closing the contacts,means for actuating said lever comprising a crank arm, a motorfor'd'riving said crank ann, means for operatively connecting said crankarm and said lever, said connecting means including a pair of membersmovable relative to each other and connected respectively to said crankarm and said lever, and a spring means which is always worked incompression for transmitting the force for operating said lever, saidspring means yieldingly opposing such relative movement of said pair ofmembers.

19. In combination, a circuit breaker having a pair of separablecontacts and an oscillatable lever for opening and closing theccntacts,vmeans for actuating said lever comprising a crank arm, almotor for driving said crank arm, means for operatively connecting saidcrank arm and saidY lever, said connecting means including a pair ofmembers each having a cylindrical portion, said portions being adapted.for telescopic arrangement and limited relative axial movement withrespect to each other, the respective ends of said por'tions havingopposed bearing surfaces, and resilient means interposed between saidopposed bearing surfaces, for yieldingly opposing relative movementbetween said portions.

20. In combination, a pair of separable contacts, an oscillatable leverfor opening and closing said contacts, means for oscillating said leverto actuate said contacts comprising a driving means, means foroperatively connecting said driving means and said lever said connectingmeans including a pairvof members, mounted-for limited telescopingmovement with respect to each other and having opposed bearing surfaces,a spring interposed between said bearing surfaces for yieldinglg,1opposing relative movement between said. members, said connecting meansbeing capable of transmitting both compressional and tensional loadswith said spring always Working in compression.

TURE LINDSTROM. 25-

